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What a fantastic post, showing your worth there my old boy I'v came out the shadows after 2 years, I allowed my personal life to leak through and became nagative rather than constructive, so for the good of the forum I took a break! So after, a marriage break down, a mental break down, a bankruptcy, a house loss, I'm back lol, happier it's all over and as a single lad and know nagging wife behind my back I can come back and pick up my obsession of winter cold!!!! Promise to add meaning and illustration to my posts moving forward to a put a smile on you all and hopefully bring a 3 wk period of severe winter weather with disruption to travel

It is a long time since I have seen such a meridional 500 mb chart prediction close to the UK. NOAA 6-10 Climate Prediction Center - 6-10 Day 500mb Outlook WWW.CPC.NCEP.NOAA.GOV And the 8-14 is pretty similar; one would imagine at some point in the next 2 weeks some very cold air is possible?

People are getting frustrated by comments like this, but it is important to keep feet on the ground and there is validity to this view. Whatever occurs over the weekend and into the start of next week is going to be marginal away from high ground. Now - this isn’t to say that marginal cannot develop into something special. I’ve lived through a marginal event many years ago that turned into much less than marginal and gave a big dump of snow - but that’s once in a lifetime. Conditions next week are not ideal (yet) for the blizzard many of us would love to see. If you get lucky next week then grin from ear to ear, make a chain of snow angels and count your lucky stars - but it won’t get away from the fact that this early turn to cold is not going to create ice days immediately. I am getting more and more confident that conditions will turn genuinely cold, but it will be a slow process. The trough in situ would appear to be staying with us for the foreseeable, and while it is possible that the gfs NE solution might come to pass and pull colder conditions in more quickly it is equally possible that we might sit under a stagnant trough and live with on/off marginality out to the New Year and beyond. However.....and it’s a big However - renewed blocking from a significant +EAMT is looking likely in the longer term, meaning stronger heights and a bigger easterly draw. Add downwelling impacts from a split SSW and the direction of travel at the moment is only in one direction. Cool becoming cold becoming colder. So - sit tight. Ride your luck next week and fingers crossed some folk get some snow, even if wet and relatively temporary. But be aware that this is just the beginning...........

Morning all. I have an update from the team over here in relation to the above post sent yesterday morning. Based on the current consistency shown by the models this morning , the outer perimeter results shown by the snow model computer increases the risk of snow now to 40 % during the period 29th /30th Dececember. They forecast spreading out of the 1000-500mb thickness ( dam ) value of 528 or slightly below over England and Wales especially. These values would be in the range for snow to occur. The exact location cannot yet be determined ( maybe with-in 48hours period if current synoptic persist ). By New Year they expect the trough to align its axis from Greenland to Northern Germany , which is good news for extending the colder and possibly snowy conditions with-in the British Isles . C

Good explanation of the role of heights. An added bit from me for those newer to snow forecasting, on winds. The thermal gradient through the atmosphere means that temperatures cool by around 2/3C for every 1000ft gained vertically. In winter however, there is a strong tendency for this to be "cancelled out" near the surface and cooler temperatures to be parked up here. In a situation with lower heights, winds are much lighter. This effectively allows the surface cool layer to remain in situ without this "mixing out". In the event of mixing in stronger winds, the non-inverted air aloft becomes mixed with the surface inversion cancelling it out. It also prevents adiabatic cooling - the process responsible for inversions. This means the snow when nearing the surface will melt as the air gets warmer. Let's take an example with -5C uppers at 300ft. This would give a surface air temperature of 3.75C. Too mild. Now. Imagine winds are lighter. Adibatic cooling of the surface has been allowed to develop. There is a cold layer up to 1000ft which has not been mixed out either. Temperatures between 0 and say 600 metres are 1C dew points 0C. A weather front with uppers of -3C pushes in. The layer between 600m and 1500m (uppers level) is saturated due to cloud. This means that the temperature only increases by 0.5C per 100m due to "saturated lapse rates". So at 600m our air temperature is 0.5C. So it's wet snow at 600m.. Now the snow hits the inversion. Stays as snow. Add in a bit of evaporative cooling and the air is easily below 0 throughout So you can start to see how -3C uppers can produce snow and -6C uppers rain depending on synoptics

Im not sure why some are using the "laughing" emoji for this... On my own page ive been reporting on the building of Northern blocking for a month now. A more irregular, unusual synoptic pattern has been evolving. Every proper cold spell has come about by Northern blocking so when its predicted then chances of a proper cold spell increases. Ive worked outside through the winters of 78/9 and 84/5 and this year has the same vibe about it, and thats based on current expectations that suggest Northern blocking will be a feature this winter. We are entering soon a period of cold and unsettled weather which alone is likely to produce snow. Then when you take into account the high chances of an SSW early next month, then a proper cold snowy spell later next month/into February, just like 78/9 84/5 is a realistic proposition. There is no sign, no real hint of raging zonality, nor uncle barty, lol, the outlook is colder then average and probably very cold at times. These charts are possibly the most interesting ive seen in my 16 odd years here, im not a coldie, im not ramping cold, im a weather enthusiast. Its also really great to read so many informative posts too, like @Scott Ingham who makes this site so great.

Yes great post SK as you are one of old timers on here it’s nice to see you posting again, unfortunately I fear the worst for @TEITS I know he was in ill health, physical and mental, the last time he visited this forum was a year ago he would have been all over this, with his keen eyes on strong cold clustered ens. I thoroughly enjoyed his posts, he wasn’t a fan of teleconnections so there were some tensions there sometimes, but he often went on based on experience and they were insightful. I pray that he is just not posting anymore but.. Here’s hoping for some snowy weather so we can all be cheered up! Next week seems likely to throw up some surprises.

There is guide on forecasting snow that has been lurking in the learners area for many years written by John Holmes who knows a thing or two about it. And I will just add that when dealing with 850mb temps make sure not to get the thermodynamic equations muddled https://www.netweather.tv/forum/topic/23729-will-it-snow/

just on twitter Glosea says yes to SSW

24 hours down the line. Wedge is the word of the day

You need to be creative with meteorology. If you look closely the UK is actually exceptionally cold.

*Metoffice upgrade alert *... Snow possible to lower levels in the period between Christmas and NY.... Eyes down for 12zs. . Upgrades please NWP !!

We always get winds off of the sea. We're an island

@TEITShas been on my mind as well. I hope he’s still with us, and not anything else . apologies Mods but, it’s the season for thinking of others. The old names who’ve been around for so long, are noticed when they go quiet.

What an outstanding post.

Yes, i think thats where these charts could go, theres a slight pressure rise to our north, troughing sinking south.. This winter really has great potential for some proper winters weather and its no exageration to think its going along similar lines to 78/9, 84/5 ..... and im no coldie... We are heading for a lengthy spell of cold unsettled...

Not that it will be to everyone's taste, but Saturday in to Sunday could be extremely lively as a vigorous cold front moves South and East. A large temperature gradient between air masses may produce a very active squall line with thunder/hail mixed in, as well as some nasty gusts of wind. Something of interest for those who enjoy lively weather!

P12 is just.. -16c uppers in East Anglia/Kent from a northerly! 'tHE uPPeRs aREn'T cOLd eNOuGh'

@inghams85 (sorry, don't know what this is. Can't delete it! ) Just for fun............like many on here, I lurk here for hours on end and never post. (Can't read models well enough to add anything noteworthy) Does anyone else get so wrapped up in this thread that when the Mrs asks what's the weather doing tomorrow, you haven't got a clue!!! But you can tell them the possibilities of 7 days time!! Haha Great group, very informative, lots of bants and lots of pretty pictures (jokes) Merry xmas to you all, hope we get some of what the models are showing (not all of it though!)

As @That ECM said the uppers do look marginally better on this run which is brilliant, but I’m going to reserve judgement until terrier drops in later. Fingers crossed!

being a very level headed former professional meteorologist I think this is the closest JH gets to a ramp

Day after day of great charts. Day after day of continued fantastic potential. We are being treated at the moment. Model watching at its best. Despite SK's brilliantly put post earlier, I'm sure the 850hpa 'debate' will rumble on. Ask yourself though, on any given model run do you check out the 850mb charts first and then (if at all) look at the the 500mb charts? Because if you do, you have definately got your priorities all wrong...

Long-time lurker here. Set up an account just to thank you for this cracking post! It's posts like this that really help people like me get in to the hobby.

As frustrating as it might be regarding the 850 values I think it’s a case of a wait and see regarding any potential snow . Surprises can pop up with the set up. After the low fills it’s likely a shortwave will move se on the eastern flank of the Atlantic block . That could provide more widespread interest . Detail this far out is difficult but the overall pattern is condusive to a prolonged period of below average temps with snow chances . Not the depth of cold that we’d like to see but a whole lot better than what could have been served up at this time of the year .

Think we all need to be careful what we wish for. But hey ho here goes Booooooooom

Where’s the isobars gone? This would be a very cold solution. Where you have snow cover, severe cold nights.

Do you ever have a day off?

Glosea on-board, properly.

Looking at the latest bbc long rang forecast significant snow next week and not just for the north..

The big story for me is the upgrade in 850s. Look at the 29th. Massive upgrade. Prospecte definitely look better for snow betweem Christmas and New Year

The trouble is, ive seen many such posters leave this site because of the stupid behaviour, its completely disrespectful and brings the site down. I usually produce evidence that suspected cold isnt coming, but this year i cannot find anything! All i can see from an unbiased pov is growing evidence for a real winter.

It’s a shame that app is about as useful as a handbrake on a canoe though.

Mods please pin a link to Snowkings outstanding post to each and every MOD thread for the rest of time. Just brilliant. Talking of brilliant, this mornings runs are upping the ante, short, medium and long term. Best model watching for years. Uppers seem a bit marginal to me though.

I like it - VAR for weather models.

I feel sorry for snowking, he’s got about 150 emails in his indox to get rid of Quality post

Snow depth from ECM shows 15cm for parts of the south and widely 10cm+ its a slight shift east from yesterday...

I don’t understand how anyone can be negative about the current output.. just baffles me.

Outstanding post. Thank you.

No complaints about the 00z output from me. A blocked Atlantic across the board. Yes the cold air isn’t QUITE there for the period immediately after Christmas but that could well get upgraded and anywhere with altitude, especially in the north, may strike it lucky. Normally at this stage, into FI, we’d be seeing signs of the ridge flattening with the Atlantic taking over. It’s really reassuring to see continued bouts of blocking continuing to crop up - a signal that this could be a fairly extended spell of below average temps if we’re lucky. It would be really beneficial for us if we could somehow get the synoptics to align to deliver some proper Arctic air (-10C at 850 hPa) at some stage. This would allow more surface cooling and could make a difference when it comes to more marginal events down the line. As for NWS’s comments about easterlies - yes these benefit the Pennines, but for large areas of the NW, especially closer to the Irish Sea, a deep cold convective WNW’ly can actually be our biggest snow maker - think December 2009. Definitely the most interesting model watching for a considerable time. Reminds me a bit of the run up to December 2009 when it looked consistently promising for days on end - the air was just that bit colder back then to give more guaranteed snow opportunities for lower elevations. All in all it’s looking very good.

Nothing mild on the 18z GFS run, but if it's snow you want, fair bit of marginality initially when the low drops over the UK, higher ground favoured, until we tap into some colder air from the NE Tuesday next week onwards. And yes, I'm not basing this solely on T850s. For once though, the UK seeing some of the coldest air in Europe, bar northern Scandinavia. The Iceland block and low heights over Europe very exciting to see too in FI. Not out the realms of posibility either, likely we'll see more and more eye candy going forth into January, as the expected +EAMT starts to have an impact on the NH trop patterns and the SPV too.

Why? They are absolutely relevant in this situation regardless of the excellent and relevant post earlier (as are the other 9 or so factors re snow). Anybody on this forum who ignores this is setting themselves up for an almighty fall. Those of us who have been around here for years know full well that the size of the hangover is directly proportionate to the levels of ramping and there is some shameless ramping going on in here tonight. Just because a message doesn't attract 'likes' it doesn't mean its wrong. Peeps would be well advised to take into account the views of the naysayers in order to keep themselves grounded. I'm on the fence a bit personally at present (maybe a bit of IMBYism creeping in !) and am watching with interest how things develop. Also an SSW doesn't guarantee anything whatsoever, it merely allows a roll of the dice. Its still perfectly possible to roll a '1' rather than a '6'. I noted John Holmes posted that the possibility of more significant cold is certainly present and that is certainly worth taking into account as John doesn't ramp, but its not guaranteed.

Deep purple anyone? Very rare if that comes off.

It means you won’t be complaining about the uppers anymore.

Last 1 until later.. but we have classic deep jet synoptic.. so we can now start looking via- output.. for own cold pooling creations... which are susceptible in this classic set up... your 850 hpa anguish.. will I think soon be.. quashed...@keep watching!!

Agreed. Every once in a while there's a contribution which should be framed and pinned as a reference point for everyone. This is such an occasion.

Morning all Quick summary/snapshots from the latest UKV from Christmas Eve into the early hours of the 27th. NW/N/NE Scotland snow showers early AM on Christmas Eve. 24/12: 03:00 The above green blob out in the North Sea is what could land in Eastern parts of England later on that day and deliver a wintry mix! (See chart below) 12:00 25/12: 18:00 Wet evening/night for West/Central Scotland. 26/12: 18:00 More widespread soaking and windy for much of NW UK and parts of Ireland. 27/12: 03:00 Our next batch of cold air is moving in from the NW - wintry showers with snowfall over high ground at this stage for favoured areas. 03:00 As always the above charts all subject to much change/timing at this range! All the best to you all!

Anyone else think that the ECM is a confused synoptic mess by day 10 this evening? I do. It looks like it is getting signals from everywhere and can’t make head or tail of them!

You’d be waiting a long time, it doesn’t exist any more! ^ Great split in the strat vortex at the end of the 12z GFS. This is an absolutely fascinating period of model watching, and it is taking up so much time, which is great because there is sod-all else to do, and even less come the inevitable January lockdown.

BOOM! - This is chart of the day so far for me, forget the slushfests, lets get a proper cold spell in!

Amazing GEM. Surface Easterly then a "low of polar origins" about to dive SE.